
(a) SpeedLimit
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Refer to [1]}. The observation space (\(\mathcal {S} \in \mathbb {R}^33\) ) contains ego-information, including position, linear velocity, quaternion, the angular velocity, the feet contact forces, etc. The action space (\(\mathcal {A} \in \mathbb {R}^8\) ) denotes the forces applied to each motors. The four-legged ant is rewarded for running along the avenue, which is calculated by the forward distance towards the target \(x_\text{target} = +\infty \) . However, it is constrained with its linear velocity \(\dot{x}\) . In our experiments, the agent receives \(+1\)  cost signal if \(|\dot{x}| > 0.15 m/s\)  or the ant is out of the yellow boundary , i.e., \(|y| > 2 m\) .

